1. Field of the Invention
This invention relates to time-delayed propellant devices. More particularly, it relates to the delayed release of an active agent from a propellant-type device by employing materials susceptible to displacement by various actuating factors present in the propellant device.
More particularly, the present invention employs materials susceptible to displacement at ambient temperature by an actuating factor such as a compressed propellant or a solvent.
2. Related Disclosures
Devices which allow for the total or partial release of an active agent from a propellant device, e.g., aerosol containers, are known. These devices are in the form of valves, overcaps, actuators, button lock action devices and the like. Examples of these devices may be found in U.S. Pat. Nos. 4,426,025, 3,765,573, and in the Handbook of Aerosol Technology, 2nd Ed., page 85, Kreiger Publ.
The main disadvantage of the total-release containers is their immediate actuation which exposes the operator to the often hazardous, noxious or unpleasant contents of the containers. Thus, devices with delayed actuation are desirable to prevent direct contact of the operator with the content of the container.
Some attempts for delayed release of the content of various containers were made previously. The resulting devices are mostly applicable and/or suitable for specific purpose only.
Dispensers with delayed opening of a water-soluble seal which dissolves when coming in contact with water in the washing machine are described in U.S. Pat. No. 3,399,806. Such dispensers also contain a second seal between the water-soluble seal and the dispensers, contents, which second seal must be broken or removed mechanically by the operator in order for the water-soluble seal to become functional.
U.S. Pat. No. 3,800,878 describes a fire extinguisher utilizing a temperature-responsive eutectic material in conjunction with an auxiliary seal that isolates the eutectic material from the pressurized fluid of the container. The eutectic material exposed to the heat melts and releases the pressurized content of the container which, in turn, opens the auxiliary seal. The combination such as one described above can be only used for certain types of containers, such as sturdy fire extinguishers, as it is rather dangerous to employ together such actuation stimuli as heat and pressure because the heat increases the pressure in the container which may break and/or explode.
Another device disclosed in U.S. Pat. No. 2,759,768 and useful for atomizing pressurized gas or liquid insecticides also combines two elements for its delayed release. This device comprises a solvent-soluble shutter plate positioned between the nozzle and the interior of the bomb. The shutter plate is supplemented with a lining membrane susceptible to pressure but resistant to the solvent. Structurally, the device is rather complicated in that it needs a build-in spring underneath said shutter to push the shutter through the perforator. Also, before the unit can be activated, the solvent needs to be poured manually into the nozzle cylinder, making it impractical for ordinary use. First, the solvent needs to be stored separately; second, manually adding the solvent to the nozzle is time-consuming; and third, it exposes the operator to the solvent. In alternative, the disclosed device uses a built-in knife which cuts the base of the box filled with a solvent. Again, the device with a built-in knife is structuraly complicated, more expensive to manufacture and impractical to handle.
A container for dispensing fumigants employing a kind of delayed actuation is disclosed in U.S. Pat. No. 2,244,302. The delayed release is caused by melting of the low-melting metal alloy plug sealing the outer tube of the container. Surrounding, the seal is the ring of solid combustible material or some other flammable material. To release the contents of the container it is necessary to manually ignite the combustible material which then generates heat, which heat fuses the metal seal of low-melting alloy. This kind of heat-sensitive plug can only be used for containers of which the contents are not explosive and flammable and those containers which are not under pressure. It also requires the operator to ignite the material which creates the danger of starting a fire.
The present invention provides a simple, inexpensive, safe, effective, practical and easy-to-handle means for delayed actuation, avoiding at the same time the disadvantages of the previously known total-release devices. It provides a time-delayed actuation and release for all kinds of total-release propellant type devices such as foggers, fumigators, insecticidal sprays and bombs, paint capsules, gas bombs, aerosols, oven cleaners, tear gas grenades, smoke grenades, explosives and other devices without involving unnecesary, impractical or hazardous steps. Many of these propellant devices could not be activated by the previously disclosed mechanisms.